### Email Archive: panotools-devel (read-only)

 Re: [PanoTools-devel] Albers Equal Area Conic Projection From: Daniel M. German - 2007-03-24 01:42 ```I am trying to reduce the size of my mailbox and I finding some older messages. yuval> --- "Michael Gross (adv)" wrote: >> I wrote something about the changes in >> http://mdgrosse.net/pano/albersequalareaconic.txt yuval> thanks! to understand it better, I have a couple of yuval> questions: yuval> P"60.0 20.0" yuval> are these the two standard parallels? yuval> ? Yes. yuval> let's call them P1 and P2, as in P"P1 P2". yuval> What is the possible value range for P1 and P2? Presented by H.C. Albers in 1805, takes two parameters (its standard parallels, corresponding to the parallels where the cone of projection is secant to the sphere). When both are one of the poles then it becomes a Lambert Equal Area Azimuthal. When both are the horizon, it becomes a Lambert Equal Area Cylindrical. yuval> does one of them have to be always larger than the yuval> other? or are there no limitations? Imagine a cone. The cone cuts the sphere at the place where the parallels are. The order of the parallels does not matter, but their sign does. yuval> is P1=P2 acceptable? if it is not acceptable, will yuval> there be an error code returning? Yes, see above. If P1=P2=90, or 0 then an error is returned. It should automatically compute the corresponding cylindrical or azimuthal. yuval> what are sensible values? I really don't like the projection :) yuval> what is the effect of a larger/smaller difference yuval> between P1 and P2? The cone becomes tangent to the sphere at that point. yuval> what is the effect of smaller/larger numbers? Load an equirectilinear in hugin and play with it. yuval> I mean: it is intuitive to me that there will be two yuval> factors changing: the height of the cone (the yuval> development will be more or less vertically stretched) yuval> and its width (which will cover more or less of the yuval> circle). I am trying to understand how the two input yuval> factors relate to these two output observation. yuval> Yuv yuval> __________________________________________________ yuval> Do You Yahoo!? yuval> Tired of spam? Yahoo! Mail has the best spam protection around yuval> http://mail.yahoo.com yuval> ------------------------------------------------------------------------- yuval> Take Surveys. Earn Cash. Influence the Future of IT yuval> Join SourceForge.net's Techsay panel and you'll get the chance to share your yuval> opinions on IT & business topics through brief surveys - and earn cash yuval> http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV yuval> _______________________________________________ yuval> PanoTools-devel mailing list yuval> PanoTools-devel@... yuval> https://lists.sourceforge.net/lists/listinfo/panotools-devel -- DMG ```

[PanoTools-devel] Albers Equal Area Conic Projection Michael Gross (adv) <adv@md...>
 [PanoTools-devel] Albers Equal Area Conic Projection From: Michael Gross - 2006-12-28 01:48 ```Hello I implemented the Albers Equal Area Conic Projection (http://mathworld.wolfram.com/AlbersEqual-AreaConicProjection.html). Example: http://mdgrosse.net/pano/albersequalareaconic.jpg Unfortunately I had to change quite a lot in panotool because I needed an additional parameter in the p-line of the input script (the phi2) and also some persistent information for the transformation functions which I both included as array "formatparam" into the Image structure. If still someone is interested: http://mdgrosse.net/pano/albersequalareaconic.diff Example p-line of the input script: p f10 P"60.0" w1024 v360 n"TIFF_m" The P-parameter is the phi2. Michael ```

 Re: [PanoTools-devel] Albers Equal Area Conic Projection From: Daniel M. German - 2006-12-28 04:11 ```Hi Michael, Thanks for the implementation. WHen I started implementing new projections about 3 weeks ago it was clear that some of them needed an extra parameter. I look at your diff and it looks complex. Would you mind describing what you did? perhaps a description in the form of a ChangeLog would be useful. Also why did you decide to replace "distance" with "distanceparam"? thanks! daniel Michael Gross (adv) twisted the bytes to say: Michael> Hello Michael> I implemented the Albers Equal Area Conic Projection Michael> (http://mathworld.wolfram.com/AlbersEqual-AreaConicProjection.html). Michael> Example: http://mdgrosse.net/pano/albersequalareaconic.jpg Michael> Unfortunately I had to change quite a lot in panotool because I needed Michael> an additional parameter in the p-line of the input script (the phi2) and Michael> also some persistent information for the transformation functions which Michael> I both included as array "formatparam" into the Image structure. Michael> If still someone is interested: Michael> http://mdgrosse.net/pano/albersequalareaconic.diff Michael> Example p-line of the input script: p f10 P"60.0" w1024 v360 n"TIFF_m" Michael> The P-parameter is the phi2. Michael> Michael Michael> ------------------------------------------------------------------------- Michael> Take Surveys. Earn Cash. Influence the Future of IT Michael> Join SourceForge.net's Techsay panel and you'll get the chance to share your Michael> opinions on IT & business topics through brief surveys - and earn cash Michael> http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV Michael> _______________________________________________ Michael> PanoTools-devel mailing list Michael> PanoTools-devel@... Michael> https://lists.sourceforge.net/lists/listinfo/panotools-devel -- Daniel M. German "It is useless to punish a man unless he knows why he is punished... Punishment must be unusual R. Heinlein -> or it serves no purpose." http://turingmachine.org/ http://silvernegative.com/ dmg (at) uvic (dot) ca replace (at) with @ and (dot) with . ```

 Re: [PanoTools-devel] Albers Equal Area Conic Projection From: Michael Gross (adv) - 2006-12-29 00:03 ```Hello I updated the diff file. There were some bugs and also it is now possible to specify both standard parallels in the p-line, for example: p f10 P"60.0 20.0" w1024 v360 n"TIFF_m" I wrote something about the changes in http://mdgrosse.net/pano/albersequalareaconic.txt I use the MakeParams directly as parameter for the transformation functions. With the declared distance-macro it was not possible to use mp->distance. If you have any suggestion, how I could make this parameter-thing better (or less "invasive") I will modify it. Michael Daniel M. German wrote: > Hi Michael, > > Thanks for the implementation. WHen I started implementing new > projections about 3 weeks ago it was clear that some of them needed an > extra parameter. > > I look at your diff and it looks complex. Would you mind describing > what you did? perhaps a description in the form of a ChangeLog would > be useful. > > Also why did you decide to replace "distance" with "distanceparam"? > > thanks! > > daniel > > > > Michael Gross (adv) twisted the bytes to say: > > Michael> Hello > Michael> I implemented the Albers Equal Area Conic Projection > Michael> (http://mathworld.wolfram.com/AlbersEqual-AreaConicProjection.html). > > Michael> Example: http://mdgrosse.net/pano/albersequalareaconic.jpg > > Michael> Unfortunately I had to change quite a lot in panotool because I needed > Michael> an additional parameter in the p-line of the input script (the phi2) and > Michael> also some persistent information for the transformation functions which > Michael> I both included as array "formatparam" into the Image structure. > > Michael> If still someone is interested: > Michael> http://mdgrosse.net/pano/albersequalareaconic.diff > > Michael> Example p-line of the input script: > p f10 P"60.0" w1024 v360 n"TIFF_m" > > Michael> The P-parameter is the phi2. > > > Michael> Michael > > > > Michael> ------------------------------------------------------------------------- > Michael> Take Surveys. Earn Cash. Influence the Future of IT > Michael> Join SourceForge.net's Techsay panel and you'll get the chance to share your > Michael> opinions on IT & business topics through brief surveys - and earn cash > Michael> http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV > Michael> _______________________________________________ > Michael> PanoTools-devel mailing list > Michael> PanoTools-devel@... > Michael> https://lists.sourceforge.net/lists/listinfo/panotools-devel > > -- > Daniel M. German "It is useless to punish a man > unless he knows why he is punished... > Punishment must be unusual > R. Heinlein -> or it serves no purpose." > http://turingmachine.org/ > http://silvernegative.com/ > dmg (at) uvic (dot) ca > replace (at) with @ and (dot) with . > > > ```

 Re: [PanoTools-devel] Albers Equal Area Conic Projection From: yuval levy - 2006-12-29 12:17 ```--- "Michael Gross (adv)" wrote: > I wrote something about the changes in > http://mdgrosse.net/pano/albersequalareaconic.txt thanks! to understand it better, I have a couple of questions: P"60.0 20.0" are these the two standard parallels? ? let's call them P1 and P2, as in P"P1 P2". What is the possible value range for P1 and P2? does one of them have to be always larger than the other? or are there no limitations? is P1=P2 acceptable? if it is not acceptable, will there be an error code returning? what are sensible values? what is the effect of a larger/smaller difference between P1 and P2? what is the effect of smaller/larger numbers? I mean: it is intuitive to me that there will be two factors changing: the height of the cone (the development will be more or less vertically stretched) and its width (which will cover more or less of the circle). I am trying to understand how the two input factors relate to these two output observation. Yuv __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com ```

 Re: [PanoTools-devel] Albers Equal Area Conic Projection From: Michael Gross (adv) - 2006-12-29 16:34 ```Hi The two parameters are the standard parallels in degrees. The range is=20 from 90=B0 to -90=B0. Along these these parallels there is no angular and= no=20 scale distortion. The ordering of the parameters has no effect. Depending on phi1 and phi2 the shape of the projection is differently=20 curved. You can also make phi1=3Dphi2. When phi1=3Dphi2=3D90 then the=20 projection is circle. With phi1=3Dphi2=3D-90 the projection is also a cir= cle=20 but the other way round (i.e. 90: tripod is in the center, -90: sky is=20 in the center). With phi1=3D-phi2 you get also a circle where the zenith and nadir are=20 both located somewhere in the circle. phi1=3D90, phi2=3D0 gets you a=20 half-circle. A few examples: http://mdgrosse.net/pano/albers_-90_-90.jpg http://mdgrosse.net/pano/albers_-90_0.jpg http://mdgrosse.net/pano/albers_0_-60.jpg http://mdgrosse.net/pano/albers_0_10.jpg http://mdgrosse.net/pano/albers_0_60.jpg http://mdgrosse.net/pano/albers_90_-90.jpg http://mdgrosse.net/pano/albers_90_0.jpg http://mdgrosse.net/pano/albers_90_90.jpg http://mdgrosse.net/pano/albers_9_10.jpg yuval levy wrote: > --- "Michael Gross (adv)" wrote: >> I wrote something about the changes in >> http://mdgrosse.net/pano/albersequalareaconic.txt >=20 > thanks! to understand it better, I have a couple of > questions: >=20 > P"60.0 20.0" >=20 > are these the two standard parallels? > ? >=20 ```

 [PanoTools-devel] adding projections was: Albers Equal Area Conic Projection From: Daniel M. German - 2006-12-29 19:29 ```Hi Everybody, I like the projection and I will incorporate the code (I just need a few days). It is important also to remember that some projections are special cases of others. For example, oblique projections are a more general projection than "regular ones", but obliques are not necessary because one can rotate the panorama before the projection is made (which is not usually done with the Earth :) In fact, if we allow the specification of the two parallels, the ALbert projection is a general case of the Lamberts (both cylindrical--0,0 I think-- and conic--90,-90). Pablo, what is your opinion in extending the parser with a multi-value parameter? I would think that it will be clearer to have 2 parameters instead of 1. This is because some projections need only one. And this, of course, will affect nona. dmg Michael> Hi Michael> The two parameters are the standard parallels in degrees. The r= ange is=20 Michael> from 90=B0 to -90=B0. Along these these parallels there is no a= ngular and no=20 Michael> scale distortion. The ordering of the parameters has no effect. Michael> Depending on phi1 and phi2 the shape of the projection is diffe= rently=20 Michael> curved. You can also make phi1=3Dphi2. When phi1=3Dphi2=3D90 th= en the=20 Michael> projection is circle. With phi1=3Dphi2=3D-90 the projection is = also a circle=20 Michael> but the other way round (i.e. 90: tripod is in the center, -90:= sky is=20 Michael> in the center). Michael> With phi1=3D-phi2 you get also a circle where the zenith and na= dir are=20 Michael> both located somewhere in the circle. phi1=3D90, phi2=3D0 gets = you a=20 Michael> half-circle. Michael> A few examples: http://mdgrosse.net/pano/albers_-90_-90.jpg http://mdgrosse.net/pano/albers_-90_0.jpg http://mdgrosse.net/pano/albers_0_-60.jpg http://mdgrosse.net/pano/albers_0_10.jpg http://mdgrosse.net/pano/albers_0_60.jpg http://mdgrosse.net/pano/albers_90_-90.jpg http://mdgrosse.net/pano/albers_90_0.jpg http://mdgrosse.net/pano/albers_90_90.jpg http://mdgrosse.net/pano/albers_9_10.jpg Michael> yuval levy wrote: >> --- "Michael Gross (adv)" wrote: >>> I wrote something about the changes in >>> http://mdgrosse.net/pano/albersequalareaconic.txt >>=20 >> thanks! to understand it better, I have a couple of >> questions: >>=20 >> P"60.0 20.0" >>=20 >> are these the two standard parallels? >> ? >>=20 Michael> ---------------------------------------------------------------= ---------- Michael> Take Surveys. Earn Cash. Influence the Future of IT Michael> Join SourceForge.net's Techsay panel and you'll get the chance = to share your Michael> opinions on IT & business topics through brief surveys - and ea= rn cash Michael> http://www.techsay.com/default.php?page=3Djoin.php&p=3Dsourcefo= rge&CID=3DDEVDEV Michael> _______________________________________________ Michael> PanoTools-devel mailing list Michael> PanoTools-devel@... Michael> https://lists.sourceforge.net/lists/listinfo/panotools-devel -- Daniel M. German "If builders built buildings the way computer programmers write programs, the first woodpecker that came along would have destroyed Weinberg's law -> all civilization. " http://turingmachine.org/ http://silvernegative.com/ dmg (at) uvic (dot) ca replace (at) with @ and (dot) with . =20 ```

 Re: [PanoTools-devel] adding projections was: Albers Equal Area Conic Projection From: Pablo d'Angelo - 2006-12-30 20:46 ```Hi Everybody, Daniel M. German schrieb: > For example, oblique projections are a more general projection than > "regular ones", but obliques are not necessary because one can rotate > the panorama before the projection is made (which is not usually done > with the Earth :) > > In fact, if we allow the specification of the two parallels, the > ALbert projection is a general case of the Lamberts (both > cylindrical--0,0 I think-- and conic--90,-90). > > Pablo, what is your opinion in extending the parser with a > multi-value parameter? I would think that it will be clearer to have 2 > parameters instead of 1. This is because some projections need only > one. Yes thats probably the best way. For nona, I have already added two letter parameters, which might also be a good idea for the parameters. So for example, the new parameters could be named Pa and Pb. If an additional information is required, > And this, of course, will affect nona. For nona it is probably not very complicated. Having a nice interface in hugin is the bigger question... Maybe two sliders in the preview panel? Also, for GUI purposes, some way to query the allowed range of these parameters would be required. ciao Pablo ```

 Re: [PanoTools-devel] adding projections was: Albers Equal Area Conic Projection From: Daniel M. German - 2006-12-31 10:57 ```>> For example, oblique projections are a more general projection than >> "regular ones", but obliques are not necessary because one can rotate >> the panorama before the projection is made (which is not usually done >> with the Earth :) >> >> In fact, if we allow the specification of the two parallels, the >> ALbert projection is a general case of the Lamberts (both >> cylindrical--0,0 I think-- and conic--90,-90). >> >> Pablo, what is your opinion in extending the parser with a >> multi-value parameter? I would think that it will be clearer to have 2 >> parameters instead of 1. This is because some projections need only >> one. Pablo> Yes thats probably the best way. For nona, I have already added two letter Pablo> parameters, which might also be a good idea for the parameters. So for Pablo> example, the new parameters could be named Pa and Pb. If an additional Pablo> information is required, >> And this, of course, will affect nona. Pablo> For nona it is probably not very complicated. Having a nice interface in Pablo> hugin is the bigger question... Maybe two sliders in the preview panel? Pablo> Also, for GUI purposes, some way to query the allowed range of these Pablo> parameters would be required. Agreed. I think you need one function to call that returns all the parameters you need: max vfov, max hfov, number of parms, range of parms, etc. Pablo, I think geographers will thank you endlessly for giving them hugin to play with the way projections work. Too bad Snyder is dead. He would have been very excited with this project. I found his "PRofessional Paper" online: http://pubs.er.usgs.gov/usgspubs/pp/pp1395 It is in a weird format, so you need to download the plugin. It is a great treatise in map making. dmg Pablo Pablo> ------------------------------------------------------------------------- Pablo> Take Surveys. Earn Cash. Influence the Future of IT Pablo> Join SourceForge.net's Techsay panel and you'll get the chance to share your Pablo> opinions on IT & business topics through brief surveys - and earn cash Pablo> http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV Pablo> _______________________________________________ Pablo> PanoTools-devel mailing list Pablo> PanoTools-devel@... Pablo> https://lists.sourceforge.net/lists/listinfo/panotools-devel -- Daniel M. German "Writing a new OS only for the 386 in 1991 gets you your second F for this term. Prof. Andrew S. Tanenbaum, author of Minix, in a newsgroup posting -> to Linus Torvalds." http://turingmachine.org/ http://silvernegative.com/ dmg (at) uvic (dot) ca replace (at) with @ and (dot) with . ```

 Re: [PanoTools-devel] Albers Equal Area Conic Projection From: Erik Krause - 2007-01-01 20:13 ```On Thursday, December 28, 2006 at 2:46, Michael Gross (adv) wrote: > I implemented the Albers Equal Area Conic Projection > (http://mathworld.wolfram.com/AlbersEqual-AreaConicProjection.html). > > Example: http://mdgrosse.net/pano/albersequalareaconic.jpg Nice image, however, I'd be interested how this projection compares to the "Orientation plate" remapping described on http://wiki.panotools.org/Unusual_remappings which is already possible with old PTStitcher? best regards -- Erik Krause Resources, not only for panorama creation: http://www.erik-krause.de/ ```

 Re: [PanoTools-devel] Albers Equal Area Conic Projection From: Daniel M. German - 2007-01-10 06:11 ```HI Michael, I finally got some time to add your code for the Albers Projection. Would you mind clarifing the following points? 1. I noticed that you use an unlimited number of "internal parameters", in this case 7. I suspect you do it for optimization purposes. Is the idea that some of these parameters can be computed once, instead of in each iteration? In the current implementation albersequalareaconic_paramcheck is called every time albersequalareaconic_erect is called. 2. You seem to interpret North and negative and South as positive angles. For instance, then I provide 0 60 (as in your example below) http://mdgrosse.net/pano/albers_0_60.jpg I get the opposite to what I would expect: http://mathworld.wolfram.com/AlbersEqual-AreaConicProjection.html To get that I need to use parameters 0, -60 http://mdgrosse.net/pano/albers_0_-60.jpg 3. What do you think should be the behaviour if only 1 parameter is given?=20 Thanks a lot! -- daniel =20 Michael> Hi Michael> The two parameters are the standard parallels in degrees. The r= ange is=20 Michael> from 90=B0 to -90=B0. Along these these parallels there is no a= ngular and no=20 Michael> scale distortion. The ordering of the parameters has no effect. Michael> Depending on phi1 and phi2 the shape of the projection is diffe= rently=20 Michael> curved. You can also make phi1=3Dphi2. When phi1=3Dphi2=3D90 th= en the=20 Michael> projection is circle. With phi1=3Dphi2=3D-90 the projection is = also a circle=20 Michael> but the other way round (i.e. 90: tripod is in the center, -90:= sky is=20 Michael> in the center). Michael> With phi1=3D-phi2 you get also a circle where the zenith and na= dir are=20 Michael> both located somewhere in the circle. phi1=3D90, phi2=3D0 gets = you a=20 Michael> half-circle. Michael> A few examples: http://mdgrosse.net/pano/albers_-90_-90.jpg http://mdgrosse.net/pano/albers_-90_0.jpg http://mdgrosse.net/pano/albers_0_-60.jpg http://mdgrosse.net/pano/albers_0_10.jpg http://mdgrosse.net/pano/albers_0_60.jpg http://mdgrosse.net/pano/albers_90_-90.jpg http://mdgrosse.net/pano/albers_90_0.jpg http://mdgrosse.net/pano/albers_90_90.jpg http://mdgrosse.net/pano/albers_9_10.jpg Michael> yuval levy wrote: >> --- "Michael Gross (adv)" wrote: >>> I wrote something about the changes in >>> http://mdgrosse.net/pano/albersequalareaconic.txt >>=20 >> thanks! to understand it better, I have a couple of >> questions: >>=20 >> P"60.0 20.0" >>=20 >> are these the two standard parallels? >> ? >>=20 Michael> ---------------------------------------------------------------= ---------- Michael> Take Surveys. Earn Cash. Influence the Future of IT Michael> Join SourceForge.net's Techsay panel and you'll get the chance = to share your Michael> opinions on IT & business topics through brief surveys - and ea= rn cash Michael> http://www.techsay.com/default.php?page=3Djoin.php&p=3Dsourcefo= rge&CID=3DDEVDEV Michael> _______________________________________________ Michael> PanoTools-devel mailing list Michael> PanoTools-devel@... Michael> https://lists.sourceforge.net/lists/listinfo/panotools-devel -- Daniel M. German "You could wind up belivin'=20 that paradise is nothin' more than a feelin' Marillion -> that goes on in your mind." http://turingmachine.org/ http://silvernegative.com/ dmg (at) uvic (dot) ca replace (at) with @ and (dot) with . =20 ```

 Re: [PanoTools-devel] Albers Equal Area Conic Projection From: Michael Gross (adv) - 2007-01-10 12:18 ```Daniel M. German wrote: > 1. I noticed that you use an unlimited number of "internal parameters", > in this case 7. I suspect you do it for optimization purposes. Is the > idea that some of these parameters can be computed once, instead of in > each iteration? In the current implementation > albersequalareaconic_paramcheck is called every time > albersequalareaconic_erect is called. Its called every time but in the paramcheck-function there is an if: - if formatparamcount == 0 (no parameters are given) then they are set to default values (0, 60). - if formatparamcount == 2 (phi1 and phi2) then all the calculation is done. This results in 7 parameters. - if formatparamcount == 7 then nothing is done. - else an error is returned. So first time the function is called and the formatparamcount is set to 7 and the calculation is not done in any subsequent calls. > 2. You seem to interpret North and negative and South as positive > angles. For instance, then I provide 0 60 (as in your example below) > > http://mdgrosse.net/pano/albers_0_60.jpg > > I get the opposite to what I would expect: > > http://mathworld.wolfram.com/AlbersEqual-AreaConicProjection.html > > To get that I need to use parameters 0, -60 > > http://mdgrosse.net/pano/albers_0_-60.jpg Yes, I noticed that too and I don't know why this is. By multiplying phi and y with -1 you get the same results as in mathworld. > 3. What do you think should be the behaviour if only 1 parameter is > given? I would say that then phi1=phi2. Michael ```

 Re: [PanoTools-devel] Albers Equal Area Conic Projection From: Daniel M. German - 2007-01-11 02:54 ```Erik Krause twisted the bytes to say: Erik> On Thursday, December 28, 2006 at 2:46, Michael Gross (adv) wrote: >> I implemented the Albers Equal Area Conic Projection >> (http://mathworld.wolfram.com/AlbersEqual-AreaConicProjection.html). >> >> Example: http://mdgrosse.net/pano/albersequalareaconic.jpg Erik> Nice image, however, I'd be interested how this projection compares Erik> to the "Orientation plate" remapping described on Erik> http://wiki.panotools.org/Unusual_remappings Erik> which is already possible with old PTStitcher? I finally have an answer for you :) They are just different projections. The orientation arch is an bending of the cylindrical. One could see the Albers Conical Equal Area as the bending of a cylindrical equal area. But it will not be possible to generate a ring-like projection with the albers. At least not without some trick. It will be interesting to see how it can be used once we can use it within hugin and interactively play with it. dmg Erik> best regards Erik> -- Erik> Erik Krause Erik> Resources, not only for panorama creation: Erik> http://www.erik-krause.de/ Erik> ------------------------------------------------------------------------- Erik> Take Surveys. Earn Cash. Influence the Future of IT Erik> Join SourceForge.net's Techsay panel and you'll get the chance to share your Erik> opinions on IT & business topics through brief surveys - and earn cash Erik> http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV Erik> _______________________________________________ Erik> PanoTools-devel mailing list Erik> PanoTools-devel@... Erik> https://lists.sourceforge.net/lists/listinfo/panotools-devel -- Daniel M. German "Poetry is as exact a science Gustave Flaubert -> as geometry" http://turingmachine.org/ http://silvernegative.com/ dmg (at) uvic (dot) ca replace (at) with @ and (dot) with . ```

 Re: [PanoTools-devel] Albers Equal Area Conic Projection From: Daniel M. German - 2007-03-24 01:42 ```I am trying to reduce the size of my mailbox and I finding some older messages. yuval> --- "Michael Gross (adv)" wrote: >> I wrote something about the changes in >> http://mdgrosse.net/pano/albersequalareaconic.txt yuval> thanks! to understand it better, I have a couple of yuval> questions: yuval> P"60.0 20.0" yuval> are these the two standard parallels? yuval> ? Yes. yuval> let's call them P1 and P2, as in P"P1 P2". yuval> What is the possible value range for P1 and P2? Presented by H.C. Albers in 1805, takes two parameters (its standard parallels, corresponding to the parallels where the cone of projection is secant to the sphere). When both are one of the poles then it becomes a Lambert Equal Area Azimuthal. When both are the horizon, it becomes a Lambert Equal Area Cylindrical. yuval> does one of them have to be always larger than the yuval> other? or are there no limitations? Imagine a cone. The cone cuts the sphere at the place where the parallels are. The order of the parallels does not matter, but their sign does. yuval> is P1=P2 acceptable? if it is not acceptable, will yuval> there be an error code returning? Yes, see above. If P1=P2=90, or 0 then an error is returned. It should automatically compute the corresponding cylindrical or azimuthal. yuval> what are sensible values? I really don't like the projection :) yuval> what is the effect of a larger/smaller difference yuval> between P1 and P2? The cone becomes tangent to the sphere at that point. yuval> what is the effect of smaller/larger numbers? Load an equirectilinear in hugin and play with it. yuval> I mean: it is intuitive to me that there will be two yuval> factors changing: the height of the cone (the yuval> development will be more or less vertically stretched) yuval> and its width (which will cover more or less of the yuval> circle). I am trying to understand how the two input yuval> factors relate to these two output observation. yuval> Yuv yuval> __________________________________________________ yuval> Do You Yahoo!? yuval> Tired of spam? Yahoo! Mail has the best spam protection around yuval> http://mail.yahoo.com yuval> ------------------------------------------------------------------------- yuval> Take Surveys. Earn Cash. Influence the Future of IT yuval> Join SourceForge.net's Techsay panel and you'll get the chance to share your yuval> opinions on IT & business topics through brief surveys - and earn cash yuval> http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV yuval> _______________________________________________ yuval> PanoTools-devel mailing list yuval> PanoTools-devel@... yuval> https://lists.sourceforge.net/lists/listinfo/panotools-devel -- DMG ```

 Re: [PanoTools-devel] Albers Equal Area Conic Projection From: Daniel M. German - 2007-03-24 01:58 ```yuval> is P1=P2 acceptable? if it is not acceptable, will yuval> there be an error code returning? Daniel> Yes, see above. If P1=P2=90, or 0 then an error is returned. It should Daniel> automatically compute the corresponding cylindrical or azimuthal. After I described it I realized that the Albers becomes a Gall when P1=-P2. But the formulae we use for the Albers is undefined when P1=-P2. We should implement the Gall for the sake of compleness. dmg -- Daniel M. German "In other studies you go as far as others have gone before you, -> and" http://turingmachine.org/ http://silvernegative.com/ dmg (at) uvic (dot) ca replace (at) with @ and (dot) with . ```